The purpose of this project is to determine whether proto oncogenes are functional in human hematopoietic cells and whether these genes are involved in hematopoietic differentiation. The proto oncgenes are homologous to viral oncogenes; indeed the viral oncogenes have been derived from their cellular homologues. For example the 5 q- syndrome is a refractory anemia characterized by decreased erythroid precursors and abnormal megakaryocytic differentiation. An interstitial deletion in the long arm of chromosome 5 is characteristically present in such patients. A cellular proto oncgene (fms) has been localized near the site of deletion by workers in other laboratories. Three patients with this syndrome are followed at the NIH. DNA and RNA from their bone marrow cells is being analyzed to determine whether the fms gene is involved in a chromosomal rearrangement and whether there is an alteration in the level of expression of the fms gene as reflected by a difference in the concentration of its RNA in the cells of these patients compared to other controls.